73 340 motor worth

I think the price is good but I have a hard time believing the balance would be good after a piston swap. And like someone above said those were cast crank engines originally which requires and external balance balancer. The other thing I would add is the factory was known for a lousy balance job too. Someone might have switched it over to forged you never know unless you check. I'd take it apart and get it all checkout out before firing it up.